第六章P129中倒数第四段中
      “to realize these gains from intergration,the countries must engage in international trade.to achieve economies of scale ,each firm must concentrate its prodition in one country--either Home or Foreign.yet it must sell its output to customers in both markets.so each product will be produced in only one country and exported to the other"意思是”为了实现规模经济，各厂商必须集中生产，要么在本国，要么在外国，最终，任何产品均只在一国生产并出口到另一国。
    但是，随后在P130中第二段，又写到，由于规模经济的存在，没有一个国家能单独生产所有棉布。这不是自相矛盾吗？
    望请各位大神解答疑惑，谢谢。